In handle grip members for motorcycles, snowmobiles and so on, electric heating wires are installed within handle grip members made of synthetic rubber for warming hands of users as described in, for instance, the following Patent Document 1. In this known handle grip member with electric heater, after connecting electric power supply wires to both ends of an electric heating body of sheet type, the electric heating body sheet is wound around a core body made of a synthetic resin, and then an assembly of the core body and heating body is covered with a synthetic rubber by molding to attain electric insulation and an anti-slip surface.    The Patent Document 1: Japanese Patent Laid-opened Publication Kokai Hei 10-67366